1. Field of the Invention
The present invention relates to a method and an apparatus for manufacturing a disc cartridge accommodating therein a disc serving as an information-recording medium, and to a disc cartridge.
2. Description of the Related Art
Optical discs or magnetic discs are accommodated in cartridges so as to facilitate handling. FIG. 30 is an exploded perspective view showing an example of a conventional disc cartridge. A disc cartridge 110 includes a disc 120 as an information-recording medium, a cartridge 130 in which the disc 120 is rotatably accommodated, and a shutter 140 slidably attached to the cartridge 130.
The disc 120 is formed of a synthetic resin, such as a polycarbonate resin, a polystyrene resin, a polyolefin resin, a polymethylmethacrylate resin, or a norbornene-based resin, or aluminum or glass, and is annular. The disc 120 has an optical recording layer or a magneto-optic recording layer 121 formed on a principal plane thereof, and a chucking hub (center core) 122 made of a magnetic metal is attached to the central section thereof.
The cartridge 130 is formed in the shape of a flat box by injection molding of a thermoplastic resin, such as an ABS resin and a polycarbonate resin. The cartridge 130 consists of an upper shell 131 and a lower shell 132 coupled by screws 133. The upper shell 131 has a recording/reproducing opening 131a formed in the center of a front end (a leading end in a direction of insertion into a driving device) thereof, and first to fourth circular-arc ribs 131b to 131e formed on the same circumference of the periphery of the inner surface thereof. These ribs 131b to 131e forms a rigid circular disc accommodating section 131f for rotatably accommodating the disc 120. The lower shell 132 has a recording/reproducing opening 132a, first to fourth circular-arc ribs 132b to 132e, and a circular disc accommodating section 132f similarly to the upper shell 131, and a driving (spindle shaft-inserting) opening 132g to which the chucking hub 122 of the disc 120 faces is formed in the center of the disc accommodating section 132f. 
The shutter 140 is formed into a U-shape in cross section by punching and bending a thin metal sheet having a thickness of about 0.15 mm to 0.4 mm, such as a stainless steel sheet or an aluminum sheet, or by injection molding of an acetal resin. The shutter 140 consists of a pair of upper and lower shutter plate portions 141 and 142 superposed on the outer surfaces of the upper and lower shells 131 and 132, and a connecting portion 143 for connecting one of the ends of the shutter plate portions 141 and 142. The shutter plate portion 141 is formed so as to have a length capable of opening and closing the opening 131a of the upper shell 131, and the shutter plate portion 142 is formed so as to have a length capable of opening and closing both of the openings 132a and 132g of the lower shell 132.
The shutter 140 is slidably attached to the front end of the cartridge 130 in a state where legs 151 and 152 of a slide guide member 150 attached to the inner surface of the connecting portion 143 by screws 133 are engaged with a slide guide groove 132h provided in the lower shell 132, and the slide guide member 150 is sandwiched by the upper and lower shells 131 and 132, and is biased by a torsion coil spring 160 to keep the openings 131a, 132a, and 132g closed.
A shutter guide plate 170 for preventing an end of the longer shutter plate portion 142 from curling is attached to the outer surface of the lower shell 132. An accidental erasure-protecting member 180 is attached on the inner surface of the upper shell 131. The accidental erasure-protecting member 180 has lugs 181 on both side surfaces thereof, as shown in FIG. 31, and the lugs 181 are engaged with recesses 131i formed in the inner wall of the upper shell 131.
The thus-constructed disc cartridge 110 is assembled in a clean room using an automated assembly line so that dust does not adhere to the surface of the disc 120 and does not enter the cartridge 130 during assembly, which would affect recording and reproducing. The upper and lower shells 131 and 132 are brought together and stocked so as not to deform after being subjected to injection molding, and are placed on the assembly line on a conveyor. First, the upper and lower shells 131 and 132 are divided in a first step, the shutter guide plate 170 is bonded to the outside of the lower shell 132 in a second step, and then the accidental erasure-protecting member 180 supplied from a part feeder is engaged with the inner surface of the lower shell 132 at a predetermined position in a third step. The slide guide member 150 supplied from the part feeder is engaged with the slide guide groove 132h of the lower shell 132 in a fourth step.
Then, the disc 120 having the chucking hub 122 attached thereto and being stocked in a disc stocker is accommodated in the disc accommodating section 132f of the lower shell 132 and thereafter, the upper shell 131 that has been supplied on the line in synchrony with the lower shell 132 is coupled to the lower shell 132 by screws 133 in a sixth step. The head of the shutter plate portion 142 is inserted into a space between the shutter guide plate 7 and the lower shell 132, and holes of the connecting section 143 and the slide guide member 150 are coupled by the screws 133. Finally, the torsion coil spring 160 supplied from the part feeder is attached to the shutter 140 to complete the disc cartridge 110.
The disc cartridge 110 is sent to an inspection step to be subjected to recording/reproducing inspection. A disc cartridge 110 confirmed to have sufficient quality is sent to a packaging step to be packaged together with an index card and a label and is accommodated in a plastic case, etc., and is then sealed by a plastic film, etc., to be distributed commercially. On the other hand, a disc cartridge 110 that is determined to be defective follows the above assembly step in reverse to remove the disc 120. Thereafter, swarf of tapping screws produced at the time of fastening screws is removed by high-pressure clean air, and the disc cartridge 110 is introduced in the assembly step again, and a new disc 120 is incorporated into the disc cartridge 110.
In order to manufacture the above-described conventional disc cartridge 110, it is necessary to install and maintain a long assembly line, and a large clean room having a high-performance clean air feeder for installing the assembly line.
In addition, adjustment of an overall tact (volume of production per unit time) is required to synchronize the manufacture of the disc 120 and the assembly of the disc cartridge 110, resulting in a reduction in operational availability of the assembly line.
Furthermore, the disc cartridge 110 that is determined to be defective must follow the assembly step in reverse and follow the assembly step again. Therefore, not only are complicated operations required, but also components may be damaged and the yield of the components may be reduced when disassembling the disc cartridge 110.
Furthermore, when the tapping screws for use in coupling the upper and lower shells 131 and 132 are repeatedly removed and fastened, coupling strength of the upper and lower shells 131 and 132 is lowered. Therefore, the upper and lower shells 131 and 132 must be destroyed when the disc cartridge 110 is determined to be defective a second time.
Accordingly, it is an object of the present invention to provide a method and apparatus for manufacturing a disc cartridge for which a large-scale manufacturing facility is not required and of which manufacturing efficiency is high, and to provide a disc cartridge.
According to a first aspect of the present invention, there is provided a method for manufacturing a disc cartridge having a pair of opposing upper and lower shells, and an information recording medium disc accommodated therebetween. The method includes mutually coupling first ends of the shells; opening second ends of the shells when first ends of the shells are coupled; and inserting the disc from the second ends of the shells.
According to a second aspect of the present invention, there is provided an apparatus for manufacturing a disc cartridge having a pair of opposing upper and lower shells, an information recording medium disc accommodated therebetween. The apparatus includes a first-end coupling device for mutually coupling first ends of the shells; and a second-end opening device for opening second ends of the shells when first ends of the shells are coupled by the first-end coupling device, wherein the disc is inserted from the opened second ends of the shells.
According to a third aspect of the present invention, there is provided a disc cartridge, wherein second ends of a pair of opposing upper and lower shells are opened when first ends of the shells are coupled, and a disc is inserted and accommodated in the shells.
According to the above feature, the second end of a semifinished cartridge having components incorporated therein is opened, and a disc is inserted from the second end. Therefore, it is possible to inspect the quality of the disc after inserting the disc, to complete a disc cartridge only from an accepted product of cartridge by coupling the second end thereof, and to remove a defective disc by opening the second end of a defective product of cartridge again.